Monomer having fluorine-containing acetal or ketal structure, polymer thereof, and chemical-amplification-type resist composition as well as process for formation of pattern with use of the same

ABSTRACT

As a polymer exhibiting improved transparency which is suitable for a resist resin used in a chemical-amplification-type resist being applicable for photolithography using exposure light at 180 nm or shorter, this invention provides a polymer comprising a repeating unit resulting from polymerization of a monomer exhibiting a polymerization activity, wherein the monomer has a fluorine-containing acetal or ketal structure represented by general formula (1): 
     
       
         
         
             
             
         
       
         
         
           
             wherein 
             R represents an atomic group containing a carbon-carbon double bond exhibiting polymerization activity; at least one of R 1  and R 2  is fluorinated alkyl group or fluorinated aryl group having 1 to 20 carbon atoms; and R 3  represents a radical selected from the group consisting of hydrogen atom, alkyl group, alkoxy-substituted alkyl group, fluorinated alkyl group, aryl group, fluorinated aryl group, aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms.

TECHNICAL FIELD

This invention relates to a novel polymer resin having afluorine-containing acetal or ketal structure in its side chain and amonomer having fluorine-containing acetal or ketal structure which isused for preparing the novel polymer resin; achemical-amplification-type resist comprising the polymer; and a processfor formation of pattern with use of the same. More specifically, itrelates to a polymer compound useful as a component resin for achemical-amplification-type resist, which is applicable in particular toformation of pattern employing far-ultraviolet light at a wavelength of180 nm or shorter as exposure light thereto; and a monomer having afluorine-containing acetal or ketal structure which is used forpreparation of the polymer resin.

BACKGROUND ART

In the field of manufacturing a variety of electronic devicesrepresented by a semiconductor device, fine processing technology in ahalf-micron level is requisite for completely meeting the requirementsof further densification and integration of the device itself. Amongothers, requirements for photolithography usable for forming a finepattern to allow for such fine processing has increasingly become moreexacting. Specifically, in the case of manufacturing a DRAM with anintegration degree of 1 G bits or higher, processing technology with aminimum line width of 0.13 μm or less is needed therefor. For complyingwith such rules, there has been employed photolithography using ArFexcimer laser (193 nm) as exposure light. For the purpose of processinga further finer pattern, development in photolithography technologyusing F₂ excimer laser (157 nm) as exposure light has progressedrecently [R. R. Kunz et al., Journal of Vacuum Science and Technology,Vol. B17(6), pp.3267–3272 (1999)].

Accordingly, there have been made, in parallel, progress in thedevelopment of resist materials adaptable to such photolithography usingF₂ excimer laser (157 nm) as exposure light. As to performance requiredfor a resist material fit to F₂ excimer laser exposure, in addition to ahigher resolving potential answering such increased fineness inprocessing size, demand for higher sensitivity is on the rise.Specifically since a laser apparatus itself is expensive and a gas usedas a laser medium has a short life in terms of F₂ excimer laser used forexposure, it is desired that a more sensitive resist material is used tominimize the quantity of exposure light required for each patterningprocess and thus to improve cost performance of the laser.

It is well known that a chemical-amplification-type resist with use of aphoto-acid generator operating as a photo-sensitizer is one of hopefulapproach for making a resist material more sensitive. Such approach aschemical-amplification-type resists have been also extensively used fora conventional resist material for KrF excimer laser exposure [e.g.,Hiroshi Ito, C. Grant Wilson, American Chemical Society Symposiumseries, Vol, 242, pp.11–23 (1984)]. For example, in JP 2-27660 A1,disclosed is a chemical-amplification-type resist for whichtriphenylsulfonium hexafluoroarsenate is used as a photo-acid generatorin combination with (p-tert-butoxycarbonyloxy-α-methylstyrene) as aresist resin. A characteristic feature of suchchemical-amplification-type resist is that chemical amplification isachieved due to multiple acceleration of reaction in such a way that thephoto-acid generator added as a photosensitizer component generates aproton acid in response to exposure light irradiation; and whenheat-treating the resist post to the exposure step, one molecule of theproton acid generated by absorption of one photon induces and catalyzesan acid catalytic reactions of a resist resin or the like. Achemical-amplification-type resist utilizes said mechanism to realizedrastically higher sensitivity in comparison with a conventional resistwith a photoreaction efficiency (reaction per one photon) of lessthan 1. Currently, majority of resist materials being under developmentfor excimer laser exposure belong to a chemical-amplification-type.

DISCLOSURE OF THE INVENTION

Furthermore, in the case of photolithography using light at a shortwavelength of 180 nm or less represented by F₂ excimer laser beam asexposure light, a resist resin constituting achemical-amplification-type resist for forming a fine pattern thereby isrequired to have a new property different from that in a resist resinmaterial used in a chemical-amplification-type resist fit toconventional ArF excimer laser (193 nm) exposure, i.e., hightransparency to exposure light at a wavelength of 180 nm or shorter.

In a photoresist fit to conventional KrF excimer laser (248 nm) or ArFexcimer laser (193 nm) exposure, such a resin as poly(p-vinylphenol) oran alicyclic resin is mainly used as a resin component thereof. Whereasthese resins show higher transparency at a wavelength of 190 nm orhigher, their photoabsorptions to light at a wavelength of 180 nm orshorter are significantly strong. Therefore, if a conventional resinsuch as poly(p-vinylphenol) or an alicyclic resin is used in achemical-amplification-type resist with aim to using light at a shortwavelength of 180 nm or less as exposure light, a large part of theexposure light will be absorbed by the resist itself in the top surfaceof the resist layer, so that the exposure light fails to reach asubstrate. Thus, a proton acid cannot be generated from a photo-acidgenerator used as a photosensitizer component over the whole resist filmin its thickness direction, which causes failure of formation of a fineresist pattern. That is, a conventional resin itself, such aspoly(p-vinylphenol) or an alicyclic resin, cannot be applied to a resincomponent constituting a chemical-amplification-type resist forphotolithography using light at a shorter wavelength of 180 nm or lessas exposure light. Accordingly, there has been strongly desired a novelresin material for a resist that exhibits higher transparency to lightat a wavelength of 180 nm or shorter, which is applicable to achemical-amplification-type resist for photolithography using light at ashort wavelength of 180 nm or less as exposure light.

In order to solve the above problems, an objective of this invention isto provide a polymer that exhibits higher transparency to light at awavelength of 180 nm or less and is useful as a resin material for aresist having acid-catalysis reactivity where a proton acid generatedfrom a photo-acid generator in a photosensitizer component is involvedas a catalyst, as well as a monomer used for preparation of saidpolymer. In addition, another objective of this invention is to providea chemical-amplification-type resist comprising said polymer as a resinfor a resist and a process for formation of pattern therewith.

For solving the above problems, we have intensely conducted studies andhave finally obtained the following finding; it is essential that anatomic group constituting a principal chain in a polymer used as a resinmaterial for a resist does not have significant absorption to light at awavelength of 180 nm or less and 130 nm or more, and further an atomicgroup contained in a side chain in the polymer, which is involved in anacid-catalytic reaction by a proton acid generated from a photo-acidgenerator in a photo-sensitizer component, also does not havesignificant absorption to light at a wavelength of 180 nm or less and130 nm or more. We have found that absorption of light at a wavelengthof 180 nm or less and 130 nm or more can be significantly reduced as thewhole polymer by selecting an atomic group having an acetal or ketalstructure as said atomic group contained in the side chain of thepolymer and further conducting fluorine substitution in the acetal orketal structure thereof. In other words, we have verified that as for amonomer used for preparation of a polymer, a monomer having an atomicgroup involved in constituting the principal chain of the polymer and anacetal or ketal structure as for an atomic group to be a modifying groupto the principal chain of the polymer is a useful monomer for preparinga desired polymer exhibiting higher transparency to light at awavelength of 180 nm or less and 130 nm or more, and thus have achievedthis invention.

That is to say, a monomer containing a carbon-carbon double bondexhibiting polymerization activity thereby and having afluorine-containing acetal structure or ketal structure represented bygeneral formula (1):

wherein

R represents an atomic group containing a carbon-carbon double bondexhibiting polymerization activity thereby;

R¹ and R² represent independently a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms.

In this aspect, said monomer may be such type of the monomercharacterized in that the atomic group represented by R has at least oneskeletal structure selected from the group consisting of ethylenederivatives, vinyl chloride derivatives, styrene derivatives,acrylonitrile derivatives, (meth)acrylate derivatives, norbornenederivatives, ester derivatives of norbornenecaroboxylic acid,tetracyclododecene derivatives, ester derivatives oftetracyclododecenecarboxylic acid, tricyclononene derivatives and esterderivatives of tricyclononenecarboxylic acid.

Embodiments of the monomer compound according to this invention mayinclude a monomer characterized in that the monomer is a (meth)acrylatederivative having a fluorine-containing acetal or ketal structurerepresented by general formula (2):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group.

Embodiments of the monomer compound according to this invention mayinclude a monomer characterized in that the monomer is a norbornenederivative or tetracyclododecene derivative having a fluorine-containingacetal or ketal structure represented by general formula (3):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is the fluorinatedalkyl group or the fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represents hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

X¹ and X² independently represent hydrogen atom or methyl group;

Z represents —CO—, methylene group or a linking group being composed ofcarbon-oxygen bond; and

m is 0 or 1.

Embodiments of the monomer compound according to this invention mayinclude a monomer characterized in that the monomer is a tricyclononenederivative having a fluorine-containing acetal or ketal structurerepresented by general formula (4):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond.

This invention also provides an invention of a polymer that can beprepared using the above monomer. Thus, an embodiment of the polymeraccording to this invention is a polymer being producible bypolymerization of one or more monomer materials containing acarbon-carbon double bond exhibiting polymerization activity thereby,wherein the polymer comprises a repeating unit being obtainable byaddition polymerization of at least one of the monomer having any one ofsuch constitutions as defined above, as one of the repeating unitscontained in the polymer. Further embodiments of the polymer accordingto this invention include a polymer being producible by polymerizationof one or more monomer materials containing a carbon-carbon double bondexhibiting polymerization activity thereby, wherein the polymercomprises a repeating unit being obtainable by ring-opening metathesispolymerization of at least one of the aforementioned monomer representedby general formula (3) or (4), as one of the repeating units containedin the polymer. In this case, the polymerization is followed by furthertreatment of hydrogenating a —CH═CH— moiety formed in the principalchain to convert into said repeating unit.

The polymer according to this invention described above may be used as aresist resin in a chemical-amplification-type resist composition.Accordingly, this invention also provides an invention of achemical-amplification-type resist composition containing the polymeraccording to this invention as a resist resin. Thus, thechemical-amplification-type resist composition according to thisinvention is A resist composition of chemical-amplification-typecomprising a resist resin and a photo-sensitizer therefor, wherein thecomposition comprises the polymer according to this invention as definedabove.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable bypolymerization of a monomer containing a carbon-carbon double bondexhibiting polymerization activity thereby, wherein the unit has afluorine-containing acetal or ketal structure represented by generalformula (1a):

wherein

R_(a) represents an atomic group being derived from an atomic groupcontaining a carbon-carbon double bond exhibiting polymerizationactivity thereby and having linkages for composing a principal chainthat are presented by polymerization;

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms.

In this aspect, said embodiments of the polymer according to thisinvention may be such type of the polymer characterized in that saidrepeating unit represented by general formula (1a) comprised in saidpolymer, the atomic group represented by R_(a) is an atomic group havinglinkages for composing a principal chain that are presented by vinylpolymerization or ring-opening metathesis polymerization, and beingderived from an atomic group having one or more skeletal structuresselected from the group consisting of ethylene derivatives, vinylchloride derivatives, styrene derivatives, acrylonitrile derivatives,(meth)acrylate derivatives, norbornene derivatives, norbornenecarboxylic acid ester derivatives of norbornenecarboxylic acid,tetracyclododecene derivatives, ester derivatives of tetracyclododecenecarboxylic acid, tricyclononene derivatives and ester derivatives oftricyclononene carboxylic acid.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable byaddition polymerization of a (meth)acrylate derivative, wherein the unithas a fluorine-containing acetal or ketal structure represented bygeneral formula (2a):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable byaddition polymerization of a norbornene derivative or tetracyclododecenederivative, wherein the unit has a fluorine-containing acetal or ketalstructure represented by general formula (3a):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

X¹ and X² independently represent hydrogen atom or methyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond; and

m is 0 or 1.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable byaddition polymerization of a tricyclononene derivative, wherein the unithas a fluorine-containing acetal or ketal structure represented bygeneral formula (4a):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable byring-opening polymerization of a norbornene derivative ortetracyclododecene derivative and then hydrogenating a —CH═CH— moietyresulting therefrom, wherein the unit has a fluorine-containing acetalor ketal structure represented by general formula (3b):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

X¹ and X² independently represent hydrogen atom or methyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond; and

m is 0 or 1.

Embodiments of the polymer according to this invention may include apolymer comprising one or more repeating units being obtainable byring-opening polymerization of a tricyclononene derivative and thenhydrogenating a —CH═CH— moiety resulting therefrom, wherein the unit hasa fluorine-containing acetal or ketal structure represented by generalformula (4b):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond.

Furthermore, in the case of said polymers according to this invention,the polymer may be such type of the polymer characterized in that thepolymer comprises, in addition to said repeating unit having afluorine-containing acetal or ketal structure represented by generalformula (2a), (3a), (4a), (3b) or (4b), one or more repeating unitsselected from the group consisting of

a repeating unit represented by general formula (5):

wherein

R⁷ and R⁸ are independently hydrogen atom or fluorine atom;

R⁹ is hydrogen atom, fluorine atom, methyl group or trifluoromethylgroup;

R¹⁰ represents a radical selected from the group consisting of hydrogenatom; linear, branched or cyclic alkyl group and fluorinated alkyl grouphaving 1 to 20 carbon atoms; a group removable by an acid; a bridgedcyclic hydrocarbon group having 7 to 13 carbon atoms containing a groupremovable by an acid thereon and norbornane-2,6-carbolactone-5-yl group;

a repeating unit represented by general formula (6):

wherein R¹¹ represents hydrogen atom or a group removable by an acid;

a repeating unit represented by general formula (7):

wherein R¹² represents hydrogen atom or a group removable by an acid;

a tetrafluoroethylene radical represented by formula (8):—CF₂—CF₂—  (8)

a repeating unit represented by general formula (9):

wherein R¹³ and R¹⁴ independently represent hydrogen atom or fluorineatom; R¹⁵ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group; R¹⁶ represents hydrogen atom, hydroxy group,hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid;

a repeating unit represented by general formula (10):

wherein R¹³ and R¹⁴ independently represent hydrogen atom or fluorineatom; R¹⁵ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group; R¹⁶ represents hydrogen atom, hydroxy group,hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid;

a repeating unit represented by general formula (11):

wherein R¹³ and R¹⁴ are independently hydrogen atom or fluorine atom;R¹⁵ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group; R¹⁶ represents hydrogen atom, hydroxy group,hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid;

a repeating unit represented by general formula (12):

wherein R¹³ and R¹⁴ are independently hydrogen atom or fluorine atom;R¹⁵ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group; R¹⁶ represents hydrogen atom, hydroxy group,hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid; and

anhydrous succindiyl (tetrahydrofuran-2,5-dion-3,4-diyl) represented byformula (13):

Additionally, the polymers according to this invention may beconstituted in such manner that the polymer comprises said repeatingunit represented by any one of general formulas (2a), (3a), (3b), (4a)and (4b) in a content of at least 5 to 90 mol % to the total number ofthe repeating units composing the polymer.

In the light of the use as a resist resin, it is preferred that thepolymer according to this invention may be a polymer characterized inthat a weight-average molecular weight of the polymer is selected in therange of 2,000 to 200,000.

On the other hand, a resist composition of chemical-amplification typeaccording to this invention is preferably a resist composition ofchemical-amplification-type comprising a resist resin and aphoto-sensitizer,

wherein the composition comprises one or more of the polymers of thisinvention having any one of the constitutions as defined above as saidresist resin and at least a photo-acid generator capable of generatingan acid by exposure light as said photo-sensitizer; and

the content of the photo-acid generator to the total amount of thepolymer and the photo-acid generator is selected in the range of 0.2 to30 wt %.

Furthermore, this invention also provides a process for formation ofpattern by photolithography utilizing a resist composition ofchemical-amplification-type according to this invention. Specifically,the process for formation of pattern of this invention is defined as aprocess for formation of pattern by photolithography utilizing achemical-amplification-type resist, comprising at least the steps of:

forming a film of the aforementioned chemical-amplification-type resistof this invention applied onto a substrate to be processed for formationof pattern thereon;

irradiating the substrate with light at a wavelength of 130 to 180 nm asexposure light in accordance with a pattern to be formed to expose saidfilm of the chemical-amplification-type resist;

carrying out baking treatment for said exposed film of thechemical-amplification-type resist;

carrying out developing treatment for said film treated by baking. Forinstance, in the process for formation of pattern according to thisinvention, F₂ excimer laser beam may be suitably employed for the lightat a wavelength of 130 to 180 nm used in said exposure step. In otherwords, the polymer of this invention comprises fluorine atoms so that itcan attain adequate transparency to light at 180 nm or shorter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing a light transmittance curve in an ultravioletrange observed for the coating film of the polymer resin obtained inExample 12.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be explained hereafter in detail.

In a monomer compound according to this invention, i.e., a monomercontaining a carbon-carbon double bond exhibiting polymerizationactivity thereby and having a fluorine-containing acetal structure orketal structure represented by general formula (1), the atomic group Rcontaining a carbon-carbon double bond exhibiting polymerizationactivity thereby may be, without limitations, any of those which exhibitadequate polymerization activity and after polymerization can form aprincipal chain to give a polymer for a chemical-amplification-typeresist with good properties. Among those, in the light of obtaining apolymer for a chemical-amplification-type resist possessing an adequatemolecular weight and transparency at an exposure light wavelength, it ispreferable to employ an atomic group having one or more skeletalstructures selected from the group consisting of ethylene derivatives,vinyl chloride derivatives, styrene derivatives, acrylonitrilederivatives, (meth)acrylate derivatives, norbornene derivatives, esterderivatives of norbornenecaroboxylic acid, tetracyclododecenederivatives, ester derivatives of tetracyclododecenecarboxylic acid,tricyclononene derivatives and ester derivatives oftricyclononenecarboxylic acid. For instance, a polymer prepared byaddition polymerization or ring-opening metathesis polymerization usinga monomer employing said atomic group having the skeletal structure asthe atomic group R containing a carbon-carbon double bond exhibitingpolymerization activity thereby consequently comprises in its principalchain a repeating unit obtainable by addition polymerization or additionpolymerization of the carbon-carbon double bond that is present in theseskeletal structure such as ethylene derivatives, vinyl chloridederivatives, styrene derivatives, acrylonitrile derivatives,(meth)acrylate derivatives, norbornene derivatives, ester derivatives ofnorbornenecaroboxylic acid, tetracyclododecene derivatives, esterderivatives of tetracyclododecenecarboxylic acid, tricyclononenederivatives and ester derivatives of tricyclononenecarboxylic acid.

In particular, suitable examples of a monomer in which an atomic group Rcontains an addition-polymerizable carbon-carbon double bond may includea (meth)acrylate derivative having a fluorine-containing acetal or ketalstructure represented by general formula (2):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group. Such a (meth)acrylate derivative of generalformula (2) can be subjected to addition polymerization to obtain apolymer corresponding thereto which comprises a repeating unitrepresented by general formula (2a):

wherein R¹, R², R⁴, R⁵ and R⁶ represent the same radicals as R¹, R², R⁴,R⁵, R⁶ defined in general formula (2), respectively.

Furthermore, suitable examples of monomer having a bridged ring framethat involves a norbornene-ring structure containing an endocycliccarbon-carbon double bond, which is ring-opening-polymerizable as wellas addition-polymerizable, in the atomic group R thereof may include anorbornene derivative or tetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecenederivative having a fluorine-containing acetal or ketal structurerepresented by general formula (3):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl-group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is the fluorinatedalkyl group or the fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

X¹ and X² independently represent hydrogen atom or methyl group;

Z represents —CO—, methylene group or a linking group being composed ofcarbon-oxygen bond; and

m is 0 or 1. Such a norbornene derivative or tetracyclododecenederivative of general formula (3) can be subjected to additionpolymerization to obtain a polymer corresponding thereto which comprisesa repeating unit represented by general formula (3a):

wherein R¹, R², R⁴, R⁵, R⁶, X¹, X² and Z represent the same as R¹, R²,R⁴, R⁵, R⁶, X¹, X² and Z defined in general formula (3), respectively;and m is an identical integer to that defined for m in general formula(3). On the other hand, the norbornene derivative or tetracyclododecenederivative of general formula (3) can be subjected to ring-openingmetathesis polymerization followed by hydrogenation of a —CH═CH— moietyresulting therefrom to obtain a polymer corresponding thereto whichcomprises a repeating unit represented by general formula (3b):

wherein R¹, R², R⁴, R⁵, R⁶, X¹, X² and Z represent the same radicals asR¹, R², R⁴, R⁵, R⁶, X¹, X² and Z defined in general formula (3),respectively; and m is an identical integer to that defined for m ingeneral formula (3).

In addition, suitable examples of monomer having a bridged ring framethat involves a norbornene-ring structure containing an endocycliccarbon-carbon double bond, which is ring-opening-polymerizable as wellas addition-polymerizable, in the atomic group R thereof may include atricyclo[4.2.1.0^(2,5)]-7-nonene derivative having a fluorine-containingacetal or ketal structure represented by general formula (4):

wherein

R¹ and R² independently represent a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,fluorinated alkyl group, aryl group and fluorinated aryl group having 1to 20 carbon atoms; and at least one of R¹ and R² is said fluorinatedalkyl group or fluorinated aryl group;

R³ represents a radical selected from the group consisting of hydrogenatom, linear, branched or cyclic alkyl group, alkoxy-substituted alkylgroup, fluorinated alkyl group, aryl group, fluorinated aryl group,aralkyl group and fluorinated aralkyl group having 1 to 20 carbon atoms;

R⁴ and R⁵ independently represent hydrogen atom or fluorine atom;

R⁶ represents hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group;

Z represents —CO—, methylene group or a linking group composed ofcarbon-oxygen bond. Such a tricyclononene derivative of general formula(4) can be subjected to vinyl polymerization to obtain a polymercorresponding thereto which comprises a repeating unit represented bygeneral formula (4a):

wherein R¹, R², R⁴, R⁵, R⁶ and Z represent the same radicals as R¹, R²,R⁴, R⁵, R⁶ and Z defined in general formula (4), respectively. On theother hand, the tricyclononene derivative of general formula (4) may besubjected to ring-opening metathesis polymerization followed byhydrogenation of a —CH═CH— moiety resulting therefrom to obtain apolymer corresponding thereto which comprises a repeating unitrepresented by general formula (4b):

wherein R¹, R², R⁴, R⁵, R⁶ and Z represent the same radicals as R¹, R²,R⁴, R⁵, R⁶ and Z defined in general formula (4), respectively.

Although the polymer according to this invention is the aforementionedpolymer comprising a repeating unit derived from the monomer representedby general formula (1), it may be, if necessary, a copolymer comprisingtwo or more repeating units. Accordingly, two or more monomers havingdifferent structures can be copolymerized to prepare a copolymer havingtwo or more repeating units in a principal chain, and in achemical-amplification-type resist according to this invention, such acopolymer can be used as a resist resin to provide a resist obtainedwith a wider variety of properties.

Furthermore, in said monomer represented by general formula (1), (2),(3) or (4) and said repeating unit represented by general formula (1a),(2a), (3a), (3b), (4a) or (4b) derived from these monomers, suitablegroups for radicals R¹, R² and R³ being components involved in thefluorine-containing acetal or ketal structure may include thoseexemplified as follows. The radicals R¹ and R² are independently aradical selected from the group consisting of hydrogen atom, linear,branched or cyclic alkyl group, fluorinated alkyl group, aryl group andfluorinated aryl group having 1 to 20 carbon atoms. More specificexamples of such a suitable linear, branched or cyclic alkyl grouphaving 1 to 20 carbon atoms may include such a group as methyl, ethyl,propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl,hexyl, cyclohexyl, norbornyl, adamanthyl, tricyclodecyl andtetracyclododecyl groups. Thus, the fluorinated alkyl group having 1 to20 carbon atoms is a fluorinated derivative of the linear, branched orcyclic alkyl group described above. More specific examples of such asuitable fluorinated alkyl group may include such a group asfluoromethyl, fluoroethyl, difluoromethyl, trifluoromethyl,trifluoroethyl, tetrafluoroethyl and pentafluoroethyl groups. On theother hand, the aryl group as used herein may include an aromatic groupwith up to 20 carbon atoms in total, which aromatic ring is optionallysubstituted with alkyl group(s) or the like. More specifically, suitableexamples of such an aryl group may include such a group as phenyl, tolyland naphthyl groups. The fluorinated aryl group is such a group that hassubstitution with fluorine(s) on said aryl group with up to 20 carbonatoms in total. More particularly, preferable examples of such afluorinated aryl group may include such a group as difluorophenyl,trifluorophenyl and pentafluorophenyl groups. Additionally, at least oneof radicals R¹ and R² may be selected from the fluorinated alkyl groupor fluorinated aryl group described above to give a fluorine-containingacetal or ketal structure.

On the other hand, the radical R³ is a radical selected from the groupconsisting of hydrogen atom, linear, branched or cyclic alkyl group,alkoxy-substituted alkyl group, fluorinated alkyl group, aryl group,fluorinated aryl group, aralkyl group and fluorinated aralkyl grouphaving 1 to 20 carbon atoms. More specific examples of a suitablelinear, branched or cyclic alkyl group having 1 to 20 carbon atoms mayinclude such a group as methyl, ethyl, n-propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, cyclohexyl, cyclohexylmethyl,norbornyl, norbornylmethyl, adamanthyl, adamanthylmethyl, tricyclodecyl,tricyclodecylmethyl, tetracyclododecyl and tetracyclododecylmethylgroups. Thus, the fluorinated alkyl group having 1 to 20 carbon atoms isa fluorinated derivative of the linear, branched or cyclic alkyl groupdescribed above. More particularly, suitable examples of the fluorinatedalkyl group may include such a group as 2-fluoroethyl, fluorooctyl,trifluoroethyl and pentafluoropropyl groups. The alkoxy-substitutedalkyl group is an alkoxy-substituted derivative of the alkyl groupdescribed above having 1 to 20 carbon atoms. The total number ofskeletal atoms in the whole molecule of the alkoxy-substituted alkylgroup is preferably chosen within 20 or less. More specific examples ofsuch a preferable alkoxy-substituted alkyl group may include such agroup as methoxyethyl, ethoxyethyl, ethoxypropyl and methoxypropylgroups.

On the other hand, the aryl group for the radical R³ may include anaromatic group with up to 20 carbon atoms in total, which aromatic ringis optionally substituted with alkyl group(s) or the like. More specificexamples of such an aryl group may include such a group as phenyl, tolyland naphthyl groups. The fluorinated aryl group is such a group that hassubstitution with fluorine(s) on said aryl group with up to 20 carbonatoms in total. More particularly, preferable examples of thefluorinated aryl group may include such a group as difluorophenyl andpentafluorophenyl groups. Furthermore, the aralkyl group is such a groupthat is an alkyl group substituted by said aryl group with up to 20carbon atoms in total. The total number of skeletal carbon atoms in thewhole molecule of the aralkyl group is preferably chosen within 20 orless. More specifically, examples of the preferable aralkyl group mayinclude such a group as benzyl and phenethyl groups. The fluorinatedaralkyl group may be typically a derivative of the aralkyl group inwhich the aryl group moiety is, for example, substituted with fluorine.More particularly, preferable examples of the fluorinated aralkyl groupmay include such a group as difluorobenzyl and pentafluorobenzyl groups.

As for the radicals R⁴, R⁵ and R⁶ which are present as substituents in askeletal structure constituting a principal chain after polymerization,in the monomer represented by general formula (2), (3) or (4) as well asthe repeating unit derived from the monomer represented by generalformula (2a), (3a), (3b), (4a) or (4b), the radicals R⁴ and R⁵ may beindependently selected from hydrogen or fluorine atoms while the radicalR⁶ may be chosen form hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group.

Furthermore, among the aforementioned (meth)acrylate derivatives havinga fluorine-containing acetal or ketal structure represented by generalformula (2), examples of a more preferable compound may include a groupof the compounds listed below.

Among the aforementioned norbornene derivatives or tetracyclododecenederivatives having a fluorine-containing acetal or ketal structurerepresented by general formula (3), examples of a more preferablecompound may include a group of the compounds listed below.

On the other hand, among the aforementioned tricyclononene derivativeshaving a fluorine-containing acetal or ketal structure represented bygeneral formula (4), examples of a more preferable compound may includea group of the compounds summarized below.

Furthermore, the polymer according to this invention may be a copolymercomprising another repeating unit which may provide aimed properties ofa polymer for a chemical-amplification-type resist, in addition to therepeating unit represented by general formula (1a), (2a), (3a), (3b),(4a) or (4b). For example, such an additional repeating unit may besuitably employed that whose corresponding monomer possesses adequatepolymerization activity such that it can be readily copolymerized withthe monomer represented by general formula (1), (2), (3) or (4).Suitable examples of such an additional repeating monomer whosecorresponding monomer has adequate polymerization activity and mayprovide a resulted copolymer with aimed performance for a resist polymerfor a chemical-amplification-type resist may include the repeating unitsrepresented by general formulas (5) to (7), formula (8), generalformulas (9) to (12) and formula (13) illustrated above.

In the repeating unit represented by general formula (5):

as for the substituents on the principal-chain frame, the radicals R⁷and R⁸ are independently hydrogen atom or fluorine atom; and the radicalR⁹ is hydrogen atom, fluorine atom, methyl group or trifluoromethylgroup. On the other hand, the radical R¹⁰ as a substituent to thecarboxy group therein may be a radical selected from the groupconsisting of hydrogen atom; linear, branched or cyclic alkyl group andfluorinated alkyl group having 1 to 20 carbon atoms; a group removableby an acid; a bridged cyclic hydrocarbon group having 7 to 13 carbonatoms containing a group removable by an acid thereon andnorbornane-2,6-carbolactone-5-yl group. More specifically, suitableexamples of the linear, branched or cyclic alkyl group having 1 to 20carbon atoms may include, but not limited to, such a group as methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl,cyclohexyl, norbornyl, isobornyl, adamanthyl and tricyclodecyl groups.The fluorinated alkyl group is a fluorinated derivative of said linear,branched or cyclic alkyl group. More particularly, preferable examplesof the fluorinated alkyl group may include, but not limited to, such agroup as fluoromethyl, fluoroethyl, fluoropropyl, difluoromethyl,trifluoromethyl, tetrafluoroethyl, pentafluoroethyl, hexafluoroisopropyland nonafluorohexyl group. The group removable by an acid means a groupwhich can be removed by an acid-catalytic reaction for regaining carboxygroup. More specifically, suitable examples thereof may include, but notlimited to, such a group as tert-butyl, tetrahydropyran-2-yl,tetrahydrofuran-2-yl, 4-methoxytetrahydropyran-4-yl, 1-ethoxyethyl,1-butoxyethyl, 1-propoxyethyl, 3-oxocyclohexyl, 2-methyl-2-adamanthyl,2-ethyl -2-adamanthyl, 1-methyl-1-adamanthylethyl,8-methyl-8-tricyclo[5.2.1.0^(2,6)]decyl,1,2,7,7-tetramethyl-2-norbornyl, 2-acetoxymenthyl, 2-hydroxymenthyl and1-methyl-1-cyclohexylethyl groups. Specific examples of the bridgedcyclic hydrocarbon group with 7 to 13 carbon atoms containing the groupremovable by an acid may include, but not limited to, such a bridgedcyclic hydrocarbon group with 7 to 13 carbon atoms containing a groupremovable by an acid as described in JP 2,856,116 B1. Similarly,.norbornane-2,6-carbolactone-5-yl group, which comprises an endocycliclactone ring therein may be also employed for the radical R⁹.

In the repeating unit represented by general formula (6):

the radical R¹¹ used therein is hydrogen atom or a group removable by anacid. Specific examples of a group removable by an acid, which issuitable for the radical R¹¹, may include, but not limited to, such agroup as tert-butyl, tert-butoxycarbonyl, methoxymethyl, ethoxyethyl,tetrahydropyranyl and tetrahydrofuranyl groups.

Furthermore, in the repeating unit represented by general formula (7):

the radical R¹² used therein is hydrogen atom or a group removable by anacid. Specific examples of a group removable by an acid, which issuitable for the radical R¹², may include, but not limited to, such agroup as tert-butyl, tert-butoxycarbonyl, methoxymethyl, ethoxyethyl,tetrahydropyranyl and tetrahydrofuranyl groups.

On the other hand, the repeating unit represented by general formula(9):

or the repeating unit represented by general formula (11):

is a repeating unit derived from a monomer corresponding thereto, whichhas, for instance, a norbornene structure in the case where n is 0 ortetracyclododecene structure in the case where n is 1, wherein it can beobtained by conducting addition polymerization or ring-openingmetathesis polymerization of the monomer, respectively and thenhydrogenating a resulting —CH═CH— moiety.

Similarly, the repeating unit represented by general formula (10):

or the repeating unit represented by general formula (12):

is a repeating unit derived from a monomer corresponding thereto, whichhas a tricyclononene structure, wherein it can be obtained by conductingaddition polymerization or ring-opening metathesis polymerization of themonomer, respectively and then hydrogenating a resulting —CH═CH— moiety.

As for the radicals R¹³, R¹⁴, R¹⁵, R¹⁶ as substituents on the polycyclicstructures in said repeating units represented by general formulas (9)or (11) and general formulas (10) or (12), the radicals R¹³ and R¹⁴ areindependently selected from hydrogen atom or fluorine atom, and theradical R¹⁵ is chosen from hydrogen atom, fluorine atom, methyl group ortrifluoromethyl group, while the radical R¹⁶ is selected from hydrogenatom, hydroxy group, hydroxyalkyl group and an acid-dissociable organicgroup having up to 20 carbon atoms which can generate a carboxy grouptherefrom by its decomposition by an acid. More specifically, suitableexamples of the hydroxy alkyl group include, but not limited to, such agroup as hydroxymethyl and hydroxyethyl group. On the other hand, theacid-dissociable organic group having up to 20 carbon atoms which cangenerate a carboxy group therefrom by its decomposition by an acidmeans, in particular, an ester type acid-dissociable organic group suchas O-substituted carboxy type. Suitable examples thereof include, butnot limited to, such a group as tert-butoxycarbonyl,tetrahydropyranyloxycarbonyl, tetrahydrofuranyloxycarbonyl,4-methoxytetrahydropyranyloxycarbonyl, 1-ethoxyethoxycarbonyl,1-butoxyethoxycarbonyl, 1-propoxyethoxycarbonyl,3-oxocyclohexyloxycarbonyl, 2-methyl-2-adamanthyloxycarbonyl,2-ethyl-2-adamanthyloxycarbonyl,8-methyl-8-tricyclo[5.2.1.0^(2,6)]decyloxycarbonyl or1,2,7,7-tetramethyl-2-norbornyloxycarbonyl, 2-acetoxymenthyloxycarbonyl,2-hydroxymenthyloxycarbonyl and 1-methyl-1-cyclohexylethoxycarbonylgroups.

Besides, the tetrafluoroethylene repeating unit represented by formula(8):—CF₂—CF₂—  (8)is obtainable by addition polymerization of a corresponding monomer, andthe anhydrous succindiyl (tetrahydrofuran-2,5-dion-3,4-diyl) representedby formula (13):

is obtainable by addition polymerization of a corresponding monomer,i.e. maleic anhydride.

The polymer according to this invention preferably comprises therepeating unit represented by general formula (2a), (3a), (3b), (4a) or(4b). In the light of performance of a polymer obtained, when forming acopolymer comprising an additional repeating unit together with them,the summed content of the repeating units represented by generalformulas (2a), (3a), (3b), (4a) and (4b) in the total repeating units isdesirably selected at least 5 mol % or more, preferably 7 mol % or more.On the other hand, in the light of polymer performance obtained, forallowing a content of the additional repeating unit combined to begenerally adjusted to 10 mol % or more, preferably to 20 mol % or moreto the whole repeating units, it is desirable to keep a summedproportion of the repeating units represented by general formulas (2a),(3a), (3b), (4a) and (4b) in total to the whole repeating unitspreferably within 90 mol % or less, more preferably within 80 mol % orless.

The polymer of this invention can be prepared by polymerizing theaforementioned monomer(s) used as starting materials by a conventionaltechnique for polymerization such as radical polymerization, anionicpolymerization, addition polymerization and ring-opening metathesispolymerization. For example, when employing radical polymerization, thereaction in dry tetrahydrofuran under an inert gas (e. g., argon ornitrogen) atmosphere can be conducted by adding an appropriateradical-polymerization initiator (for example, azobisbutyronitrile) andthen stirring and heating at 50 to 70° C. for 0.5 to 12 hours tocomplete polymerization reaction.

Alternatively, when employing, for example, addition polymerization, thepolymerization can be accelerated by using, as a catalyst, a palladiumcompound (for example, {(η³-allyl)Pd(BF₄)}, {(η³-allyl)Pd(SbF₆)},[Pd(CH₃CN)₄][BF₄]₂ or etc.) in accordance with the method of J. P.Mathew et al. disclosed in Macromolecules, Vol. 29, pp.2755–2763 (1996)or a nickel compound [bis(pentafluorophenyl)nickel-toluene complex] inaccordance with the method of T. Chiba et al. disclosed in Journal ofPhotopolymer Science and Technology, Vol. 13 (4), pp.657–664 (2000).

Alternatively, when preparing a polymer by ring-opening metathesispolymerization, examples of a metathesis catalyst applicable thereto mayinclude, but not limited to, halides of a transition metal such as W(tungsten), Mo (molybdenum) and Re (rhenium); more specifically, such asWCl₆, MoCl₅ and ReCl₃. Such a metathesis catalyst is used to initiatering-opening polymerization and then an unsaturated bond resultingtherefrom, i.e. —CH═CH— moiety is subjected to hydrogenation (additionof hydrogen atoms) using a noble metal catalyst such as palladium tosynthesize an aimed polymer. Furthermore, for using in a resist resin, aweight-average molecular weight of the polymer of this invention ispreferably selected in the range of 2,000 to 200,000.

The polymer of this invention described above is a polymer suitable foruse of a resist resin contained in a chemical-amplification-type resist.In particular, the resist composition of chemical-amplification-typeaccording to this invention can be prepared by blending at least aphoto-acid generator capable of generating an acid by exposure as aphoto-sensitizer and the polymer of this invention as a resist resin.

Furthermore, since the resist composition of chemical-amplification-typeaccording to this invention is directed to application tophotolithography using exposure light at 180 nm or shorter, a photo-acidgenerator used as a photo-sensitizer therein is desirably such aphoto-acid generator that can generate an acid by exposure to light at130 to 180 nm. For allowing an applied film to be uniformly formed by afilm formation method such as spin coating and allowing a thickness ofthe applied film to be adjusted to at least as fine size as a targetedminimum line width of a fine pattern, the resist composition ofchemical-amplification-type according to this invention is prepared in asolution form such that a mixture of components such as the polymer ofthis invention employed as a resist resin and a photo-acid generator arecompletely dissolved in an organic solvent. The organic solvent used inthe resist composition of chemical-amplification-type according to thisinvention may be, without limitations, any type of solvent which cancompletely dissolve the polymer of this invention used as a resist resinand the photo-acid generator employed as a photo-sensitizer and whichhave fluidity and viscosity suitable for forming of an uniform filmapplied by a film coating technique such as spin coating. In such acase, the organic solvent can be used alone or in combination of two ormore as appropriate.

Examples of an organic solvent meeting the above requirements mayinclude, but, of course, not limited to, such a solvent as n-propylalcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol,propyleneglycol monomethyl ether acetate, propyleneglycol monoethylether acetate, ethyl lactate, 2-methoxybutyl acetate, 2-ethoxyethylacetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate,ethyl 3-methoxypropionate, N-methyl-2-pyrrolidinone, cyclohexanone,cyclopentanone, cyclohexanol, methyl ethyl ketone, 1,4-dioxane,ethyleneglycol monomethyl ether, ethyleneglycol monomethyl etheracetate, ethyleneglycol monoethyl ether, ethyleneglycol monoisopropylether, diethyleneglycol monomethyl ether and diethyleneglycol dimethylether.

On the other hand, examples of a photo-acid generator capable ofgenerating an acid by exposure to light at 130 to 180 nm, may include,but not limited to, such a compound as triphenylsulfonium saltderivatives, diphenyliodonium salt derivatives, dialkylphenacylsulfoniumsalt derivatives, nitrobenzylsulfonate derivatives andN-hydroxysuccinimide sulfonate derivatives. For allowing adequatesensitivity in a film applied of the chemical-amplification-type resistand allowing satisfactory patterning therewith, a content of thephoto-acid generator in the resist composition ofchemical-amplification-type is preferably 0.2 wt % or more, morepreferably 1 wt % or more to the total amount of the polymer of thisinvention contained as a resist resin and the photo-acid generator. Onthe other hand, for forming an uniform film coated and preventing aresidue (scum) after development, a content of the photo-acid generatoris kept at preferably 30 wt % or less, more preferably 15 wt % or lessto the total amount of the polymer of this invention and the photo-acidgenerator. The photo-acid generator can be used alone or in combinationof two or more as appropriate.

Furthermore, in addition to the photo-acid generator employed as aphoto-sensitizer, the polymer of this invention used as a resist resinand an organic solvent dissolving them, supplemented to the resistcomposition of chemical-amplification-type according to this inventionmay be, if necessary, a variety of additives commonly used for the likeresists of chemical-amplification-type, for instance, such additionalcomponents as dissolution inhibitors, organic bases, surfactants,pigments, stabilizers, application improvers and dyes.

Beside, as the polymer of this invention exhibits high transparency toexposure light at 180 nm or less, it concomitantly exhibits highertransparency to exposure light at longer than 180 nm. Thus, if aphoto-acid generator used therein can generate an acid not only byexposure to light at 130 to 180 nm but also effectively generate an acidby irradiation with light at 180 to 220 nm, such a resist composition ofchemical-amplification-type according to this invention can be appliedto photolithography using light at 180 to 220 nm, for example, ArFexcimer laser beam as exposure light.

The resist composition of chemical-amplification-type according to thisinvention is uniformly applied on a substrate to be processed by anappropriate method such as spin coating to form a film coated in adesired thickness. Then, an intended pattern is exposed thereon withexposure light at 180 nm or less, for instance, at 130 to 180 nm and issubsequently subjected to baking, during of which heat-treatmentchemical amplification is carried on by using a proton acid generatedfrom the photo-acid generator as a catalyst therefor. In particular,during the baking treatment, for the repeating units represented bygeneral formulas (1a), (2a), (3a), (3b), (4a) and (4b) contained in thepolymer of this invention used as a resist resin, dissociativeconversion of a fluorine-containing acetal or ketal structure thereofinto —OH is conducted by using the proton acid as a catalyst, and thendevelopment is conducted using a basic solution to dissolve and removethe resin in the exposed fine region, which process can be usedsuccessfully to form the aimed fine patter. Namely, as illustratedabove, a resist composition of chemical-amplification-type according tothis invention can be preferably prepared in the form of a positive typeresist.

EXAMPLES

This invention will be more specifically explained with reference toexamples herein. These examples are just good examples for illustratingthe best modes for carrying out this invention, but do not limit thescope of this invention in any manner.

Example 1

As an example of the monomer of (meth)acrylate derivative typerepresented by general formula (2) described above, methacrylate 1having the structure below was synthesized, where a choice therefor ismade such that R¹ is trifluoromethyl group, R² is difluoromethyl group,R³ is benzyl group, R⁶ is methyl group and R⁴ and R⁵ are hydrogen atoms.

There will be described the process for synthesis of methacrylate 1 andthe conditions used therein.

In 70 mL of dry THF was dissolved 8.56 g of hexafluoroisopropanol((CF₃)₂CH—OH), and the solution was cooled to −78° C. under an argonatmosphere. To the solution was added dropwise 67 mL of a 1.6 mol/Ln-butyllithium (CH₃CH₂CH₂CH₂—Li) solution in hexane, and then themixture was stirred at 0° C. for one hour. After that, to the reactionsolution was added a solution of 5 g of benzyl alcohol in dry THF, andthe mixture was stirred at room temperature for 4.5 hours. The reactionmixture was poured into ice-water. The mixture was made acidic by addingdiluted hydrochloric acid and the organic layer was extracted withether. The extracted ether layer was washed with a saline solution anddried over anhydrous MgSO₄. After evaporation of the solvent from theether layer under a reduced pressure, the residue was distilled under areduced pressure (64 to 65° C./0.5 mmHg) to provide 3 g of a fluorinatedhemiacetal (2-benzyloxy-1,1,1,3,3-pentafluoro-2-propanol) (yield: 16%).Subsequently, in 20 mL of dry dichloromethane were dissolved 2 g of thefluorinated hemiacetal, 2.56 g of triethylamine and 8 mg ofphenothiazine. To the solution was added dropwise under ice cooling asolution of 2.21 g of methacryloyl chloride in 4 mL of dichloromethane.After stirring at room temperature for 4 hours, the reaction solutionwas diluted with 100 mL of ether, sequentially washed with 0.5 Nhydrochloric acid, 3% aqueous NaHCO₃ solution and a saline solution anddried over anhydrous MgSO₄. After evaporating ether under a reducedpressure, the residue was purified by column chromatography on silicagel (eluent: hexane/ethyl acetate=40/1) to obtain 1.7 g of the desiredmethacrylate 1 (colorless liquid, yield: 67%).

¹H-NMR (CDCl₃) δ ppm: 1.96 (3H, s), 4.74–4.89 (2H, m), 5.78 (1H, s),6.27 (1H, s), 6.65 (1H, t), 7.26–7.43 (5H, m);

IR (KBr): 1750 (νC═O), 1638 (νC═C), 1210, 1177, 1141, 1116, 1047 cm⁻¹

Example 2

As an example of the monomer of (meth)acrylate derivative typerepresented by general formula (2) described above, methacrylate 2represented by the structure below was synthesized, where a choicetherefor is made such that R¹ is trifluoromethyl group, R² isdifluoromethyl group, R³ is 2-norbornyl methyl group, R⁶ is methyl groupand R⁴ and R⁵ are hydrogen atoms.

There will be described the process for synthesis of methacrylate 2 andthe condition used therein.

A fluorinated hemiacetal (1,1,1,3,3-pentafluoro-2-(2-norbornylmethoxy)-2-propanol), by the way of the intermediate product therefor,was prepared by using 2-norbornanemethanol in place of benzyl alcohol insimilar manner to the reaction conditions described in Example 1. Then,as described in Example 1, the fluorinated hemiacetal in the way of theintermediate product and methacryloyl chloride were reacted and theresidual material was purified to obtain methacrylate 2 (colorlessliquid, yield: 65%) as desired product.

¹H-NMR (CDCl₃) δ ppm: 0.52–1.82 (9H, m), 1.97 (3H, s), 2.05–2.32 (2H,m), 3.35–3.83 (2H, m), 5.78 (1H, s), 6.27 (1H, s), 6.57 (1H, t);

IR (KBr): 2874, 2958 (νC—H), 1749 (νC═O), 1638 (νC═C), 1210, 1180, 1141,1118, 1041 cm⁻¹

Example 3

As an example of the monomer of (meth)acrylate derivative typerepresented by general formula (2) described above, acrylate 1represented by the structure below was synthesized, where a choicetherefor is made such that R¹ is trifluoromethyl group, R² isdifluoromethyl group, R³ is isobutyl group and R⁴, R⁵ and R⁶ arehydrogen atoms.

There will be described the process for synthesis of acrylate 1 and theconditions used therein.

In 120 mL of dry THF was dissolved 15 g of hexafluoroisopropanol((CF₃)₂CH—OH), and the solution was cooled to 0° C. under an argonatmosphere. To the solution was added dropwise 117 mL of a 1.6 mol/Ln-butyllithium (CH₃CH₂CH₂CH₂—Li) solution in hexane and then the mixturewas stirred at 0° C. for one hour and subsequently at room temperaturefor additional one hour. Next, to the reaction solution was added 6.62 gof isobutyl alcohol, and the mixture was stirred at room temperatureovernight. After that, to the solution containing the intermediateproduct was added dropwise 8.08 g of acryloyl chloride under ice coolingand the mixture was stirred at room temperature for 4 hours.Precipitated lithium chloride was filtered off and the filtrate wasconcentrated in vacuo. To the residue was added 300 mL of ether. Theethereal layer was washed sequentially with diluted hydrochloric acid,3% sodium bicarbonate solution and a saline solution and dried overanhydrous MgSO₄. The solvent was evaporated from the ethereal layerunder a reduced pressure. The residue was purified by columnchromatography on silica gel (eluent: hexane/ethyl acetate=20/1) toobtain 4.5 g of the desired acrylate 1 (colorless liquid, yield: 18%).

¹H-NMR (CDCl₃) δ ppm: 0.91 (6H), 1.82–1.97 (1H, m), 3.43–3.63 (2H, m),6.05 (1H, d), 6.16 (1H, dd), 6.55 (1H, d), 6.60 (1H, t);

IR (KBr): 2967, 2881 (νC—H), 1761 (νC═O), 1635 (νC═C), 1210, 1186, 1131,1103, 1042 cm⁻¹

Example 4

As an example of the monomer of (meth)acrylate derivative typerepresented by general formula (2) described above, acrylate 2represented by the structure below was synthesized, where a choicetherefor is made such that R¹ is trifluoromethyl group, R² isdifluoromethyl group, R³ is methyl group and R⁴, R⁵ and R⁶ are hydrogenatoms.

There will be described the process for synthesis of acrylate 2 and theconditions used therein.

The process was conducted, in similar manner to the reaction conditionsas described in Example 3, by using methanol in place of isobutylalcohol to obtain the desired acrylate 2 (colorless liquid, yield: 32%).

¹H-NMR (CDCl₃) δ ppm: 3.57 (3H, s), 6.07 (1H, d), 6.18 (1H, dd), 6.58(1H, d), 6.56 (1H, t);

IR (KBr): 2965, 2864 (νC—H), 1761 (νC═O), 1635 (νC═C), 1211, 1181, 1133,1101, 1045 cm⁻¹

Example 5

As an example of the monomer of (meth)acrylate derivative typerepresented by general formula (2) described above, acrylate 3represented by the structure below was synthesized, where a choicetherefor is made such that R¹ and R² are trifluoromethyl groups, R³ ismethyl group and R⁴, R⁵ and R⁶ are hydrogen atoms.

There will be described the process for synthesis of acrylate 3 and theconditions used therein.

Into 1.82 g of dry methanol was introduced 18.86 g of hexafluoroacetone,and the mixture was stirred at room temperature. After 6 hours, thereaction mixture was distilled under a reduced pressure, to obtain 11.2g of hexafluoroacetone methylhemiacetal as an intermediate fluorinatedhemiacetal. Next, in 50 mL of THF was dissolved 11.2 g ofhexafluoroacetone methylhemiacetal, and the mixture was cooled to −78°C. To the solution was added dropwise 35.5 mL of a n-butyllithiumsolution in hexane (concentration: 1.6 mol/L). After stirring for onehour, 5.14 g of acryloyl chloride was added dropwise thereto. Afterstirring for 4 hours under ice cooling, precipitated lithium chloridewas filtered off and the filtrate was concentrated in vacuo. To theresidue was added 200 mL of ether, and the ethereal layer wassequentially washed with a saline solution and water. The ethereal layerwas dried over anhydrous magnesium sulfate. After evaporation of etherunder a reduced pressure, the residue was distilled under a reducedpressure to obtain 3.06 g of the desired acrylate 3 (yield: 21%,colorless liquid).

Example 6

As an example of the monomer of norbornene derivative type representedby general formula (3) described above, the norbornene-5-carboxylaterepresented by the structure below was synthesized, where a choicetherefor is made such that m=0, Z is —CO—, R¹ is trifluoromethyl group,R² is difluoromethyl group, R³ is isobutyl group, and R⁴, R⁵ and R⁶ arehydrogen atoms.

There will be described the process for synthesis of the norbornenederivative and the conditions used therein.

To 3.03 g of acrylate 1 obtained in Example 3 was added dropwise 0.761 gof cyclopentadiene (prepared by pyrolysis of dicyclopentadiene), and themixture was stirred at room temperature overnight. The unreactedstarting materials and impurities were removed under a reduced pressureto obtain 3.64 g of the desired norbornene derivative (colorless liquid,yield: 97%).

¹H-NMR (CDCl₃) δ ppm: 0.83–0.98 (6H, m), 1.23–1.55 (3H, m), 1.80–2.04(2H, m), 2.96 (1H, s), 3.04–3.18 (1H, m), 3.28 (1H, s), 3.38–3.62 (2H,m), 5.89–6.29 (2H, m), 6.49–6.55 (1H, t);

IR (KBr): 2879, 2968 (νC—H), 1770 (νC═O), 1042, 1106, 1129, 1183, 1210cm⁻¹

Example 7

As an example of the monomer of norbornene derivative type representedby general formula (3), the 2-norbornene-5-carboxylate represented bythe structure below was synthesized, where a choice therefor is madesuch that m=0, Z is —CO—, R¹ is trifluoromethyl group, R² isdifluoromethyl group, R³ is methyl group, and R⁴, R⁵ and R⁶ are hydrogenatoms.

There will be described the process for synthesis of the norbornenederivative and the conditions used therein.

The process was conducted, in similar manner to the reaction conditionsas described in Example 6, by using acrylate 2 prepared in Example 4 inplace of acrylate 1 prepared in Example 3 to obtain the desirednorbornene derivative (boiling point: 69–70° C./0.5 mmHg, colorlessliquid, yield: 95%).

¹H-NMR (CDCl₃) δ ppm: 1.24–1.53 (3H, m), 1.91–2.02 (1H, m), 2.97 (1H,s), 3.09–3.15 (1H, m), 3.30 (1H, s), 3.54–3.57 (3H, s), 5.90–6.31 (2H,m), 6.47–6.53 (1H, t);

IR (KBr): 2877, 2982 (νC—H), 1770 (νC═O), 1043, 1107, 1132, 1178, 1210cm⁻¹

Example 8

As an example of the monomer of tetracyclododecene derivative typerepresented by general formula (3) described above, the ester derivativeof tetracyclododecene-8-carboxylic acid represented by the structurebelow was synthesized, where a choice therefor is made such that m=1, Zis —CO—, R¹ is trifluoromethyl group, R² is difluoromethyl group, R³ ismethyl group, and R⁴, R⁵ and R⁶ are hydrogen atoms.

There will be described the process for synthesis of thetetracyclododecene derivative and the conditions used therein.

A mixture of the norbornene derivative obtained in Example 7 anddicyclopentadiene were stirred at 160 to 170° C. for 10 hours. From thereaction mixture, the unreacted dicyclopentadiene was removed byevaporation under a reduced pressure. The residue was purified by silicagel column chromatography (eluent: hexane/ethyl acetate=20/1), to obtainthe desired ester derivative oftetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene-8-carboxylic acid (yield:24%).

Example 9

As an example of the monomer of tricyclononene derivative typerepresented by general formula (4) described above, the ester derivativeof tricyclo-3-nonene-7-carboxylic acid represented by the structurebelow was synthesized, where a choice therefor is made such that Z is—CO—, R¹ is trifluoromethyl group, R² is difluoromethyl group, R³ ismethyl group, and R⁴, R⁵ and R⁶ are hydrogen atoms.

There will be described the process for synthesis of the tricyclononenederivative and the conditions used therein.

A mixture of 8.55 g of acrylate 2 prepared in Example 4 and 3.7 g ofquadricyclane was stirred at 90° C. for 24 hours. The unreactedquadricyclane (tetracycle[3.2.0.0^(2,7).0^(4,6)]heptane) was removed byevaporation under a reduced pressure. The residue was distilled under areduced pressure (85–86° C./0.3 mmHg) to obtain 2.9 g of the desiredester derivative of tricyclo[4.2.1.0^(2,5)]-3-nonene-6-carboxylic acid(yield: 24%).

Example 10

As an example of the monomer of norbornene derivative type representedby general formula (3) described above, the norbornene derivativerepresented by the structure below was synthesized, where a choicetherefor is made such that m=0, Z is methylene group, R¹ and R² aretrifluoromethyl groups, R³ is hydrogen atom, and R⁴, R⁵ and R⁶ arehydrogen atoms.

Into 7.05 g of 2-norbornene-5-methanol was introduced 18.86 g ofhexafluoroacetone, and the mixture was stirred at room temperatureovernight. The reaction mixture was distilled under a reduced pressureto obtain 16.16 g ofhexafluoroacetone=(2-norbornen-5-ylmethyl)=hemiacetal (yield: 98%).

¹H-NMR (CDCl₃) δ ppm: 0.41–0.58 (1H, m), 1.08–1.93 (3H, m), 2.28–2.46(1H, m), 2.82 (1H, s), 2.94 (1H, s), 3.29–3.99 (3H, m), 5.86–6.24 (2H,m);

IR (KBr): 3435 (νO—H), 2873, 2973 (νC—H), 1770 (νC═O), 1111, 1158, 1224,cm⁻¹

Example 11

As an example of the monomer of norbornene derivative type representedby general formula (3) described above, the norbornene derivativerepresented by the structure below was synthesized, where a choicetherefor is made such that m=0, Z is methylene, R¹ and R² aretrifluoromethyl groups, R³ is methyl group, and R⁴, R⁵ and R⁶ arehydrogen atoms.

In 10 mL of dry ether was dissolved 1 g of the hemiacetal prepared inExample 10. To the solution were added 0.633 g of potassium carbonateand 0.7 g of methyl p-toluenesulfonate, and the mixture was stirred atroom temperature for 12 hours. The reaction mixture was filtered and thefiltrate was purified by silica gel column chromatography to obtain 0.47g of hexafluoroacetone=methyl=(2-norbornen-5-ylmethyl)acetal (yield:45%).

Example 12

As an example of the polymer comprising the repeating unit representedby general formula (2a) described above, there was synthesized a polymercomprising a repeating unit represented by general formula (2a) in acontent of 100 mol %, in which a choice therefor is made such that R¹ istrifluoromethyl group, R² is difluoromethyl group, R³ is norbornylmethylgroup, R⁴ and R⁵ are hydrogen atoms, and R⁶ is methyl group.

There will be described the process for synthesis of the polymer ofpolymethacrylate type and the conditions used therein.

In a 50 mL egg-plant shaped flask equipped with a reflux condenser, 6.4g of methacrylate 2 prepared in Example 2 was dissolved in 16 mL of drytoluene. To the solution was added 123 mg of azobisisobutyronitrile(AIBN) (4 mol %) as an initiator for polymerization, and the mixture wasstirred at 80° C. under an argon atmosphere. After stirring 12 hours,the reaction mixture was allowed to be cooled and poured into 200 mL ofhexane. The precipitate was collected by filtration and further purifiedby reprecipitation to obtain 0.65 g of the desired polymer (yield: 10%).As determined by GPC analysis, the polymer obtained showed aweight-average molecular weight (Mw) of 7800 (calculated in polystyreneequivalent) and a ratio of weight-average molecular weight (Mw) tonumber-average molecular weight (Mn), i. e., a dispersion index (Mw/Mn)of 1.98.

Example 13

As an example of the polymer comprising the repeating unit representedby general formula (2a) described above, there was synthesized acopolymer comprising the repeating unit of general formula (2a) in acontent of 80 mol %, in which a choice therefor is made such that R¹ istrifluoromethyl group, R² is difluoromethyl group, R³ is norbornylmethylgroup, R⁴ and R⁵ are hydrogen atoms, and R⁶ is methyl group, and therepeating unit of general formula (5) in a content of 20 mol %, in whicha choice therefor is made such that R⁷ and R⁸ are hydrogen atoms, R⁹ ismethyl group and R¹⁰ is tert-butyl group.

There will be described the process for synthesis of the copolymer ofpolymethacrylate type and the conditions used therein.

In an egg-plant shaped flask equipped with a reflux condenser, 2.5 g ofmethacrylate 2 prepared in Example 2 and 0.538 g of tert-butylmethacrylate were dissolved in 10 mL of tetrahydrofuran. To the solutionwas added 0.099 g of AIBN as an initiator for polymerization, and themixture was stirred under an argon atmosphere at 65° C. for 12 hours.After being allowed to be cooled, the reaction mixture was poured into100 mL of hexane. The precipitated polymer was collected by filtrationand purified by reprecipitation to obtain 2 g of the desired copolymer(yield: 36%). As determined by GPC analysis, the copolymer obtainedshowed an weight-average molecular weight (Mw) of 10800 (calculated inpolystyrene equivalent) and a dispersion index (Mw/Mn) of 1.84.

Example 14

As an example of the polymer comprising the repeating unit representedby general formula (2a) described above, there was synthesized acopolymer comprising a repeating unit of general formula (2a) in acontent of 70 mol %, in which a choice therefor is made such that R¹ istrifluoromethyl group, R² is difluoromethyl group, R³ is norbornylmethylgroup, R⁴ and R⁵ are hydrogen atoms, and R⁶ is methyl group, and astyrene type repeating unit of general formula (6) in a content of 30mol %, in which a choice therefor is made such that R¹¹ istert-butoxycarbonyl group.

There will be described the process for synthesis of said copolymer andthe conditions used therein.

5 g of methacrylate 2 prepared in Example 2 was reacted with 2.4 g of4-(hexafluoro-2-(tert-butoxycarbonyloxy)isopropyl)styrene, in place oftert-butyl methacrylate, in- similar manner to the polymerizationconditions described in Example 13 to prepare the copolymer composed ofthe two repeating units described above (yield: 40%). As determined byGPC analysis, the copolymer obtained showed a weight-average molecularweight (Mw) of 9500 (calculated in polystyrene equivalent) and adispersion index (Mw/Mn) of 2.11.

Example 15

As an example of the polymer comprising the repeating unit representedby general formula (2a) described above, there was synthesized acopolymer comprising a repeating unit of general formula (2a) in acontent of 70 mol %, in which a choice therefor is made such that R¹ istrifluoromethyl group, R² is difluoromethyl group, R³ is norbornylmethylgroup, R⁴ and R⁵ are hydrogen atoms, and R⁶ is methyl group, and astyrene type repeating unit of general formula (6) in a content of 30mol %, in which a choice therefor is made such that R¹¹ is hydrogenatom.

There will be described the process for synthesis of said copolymer andthe conditions used therein.

5 g of methacrylate 2 prepared in Example 2 was reacted with 1.75 g of4-(hexafluoro-2-hydroxyisopropyl)styrene, in place of tert-butylmethacrylate, in similar manner to the polymerization conditionsdescribed in Example 13 to prepare the copolymer composed of the tworepeating units described above (yield: 40%). As determined by GPCanalysis, the copolymer obtained showed a weight-average molecularweight (Mw) of 9500 (calculated in polystyrene equivalent) and adispersion index (Mw/Mn) of 2.11.

Example 16

As an example of the polymer comprising the repeating unit representedby general formula (3a) described above, there was synthesized a polymercomprising the repeating unit of general formula (3a) in a content of100 mol %, in which a choice therefor is made such that m=0, Z is —CO—,R¹ is trifluoromethyl group, R² is difluoromethyl group, R³ is methylgroup, and R⁴, R⁵ and R⁶ are hydrogen atoms.

There will be described the process for synthesis of the polymer ofpolynorbornene type and the conditions used therein.

In 3 mL of dichloromethane were dissolved 0.0182 g ofdi-μ-chlorobis[(η-allyl)palladium(II)] and 0.0453 g of silverhexafluoroantimonate (AgSbF₆), and the mixture was stirred at roomtemperature. After 20 min, the reaction mixture was filtered. To thefiltrate was added a solution of 1.489 g of the norbornene derivative(2-methoxy-1,1,1,3,3-pentafluoroisopropyl 2-norbornene-5-carboxylate)prepared in Example 7 and 0.011 g ofN,N,N′,N′-tetramethyl-1,8-naphthalenediamine in 2 mL of dichloromethane.The addition was followed by stirring at room temperature for further 20hours. After that, the mixture was poured into 50 mL of methanol. Theprecipitated resin was collected by filtration to obtain 0.715 g of thedesired polymer (yield: 48%). As determined by GPC analysis, the polymerobtained showed a weight-average molecular weight (Mw) of 18500(calculated in polystyrene equivalent) and a dispersion index (Mw/Mn) of2.44.

Example 17

As an example of the polymer comprising the repeating unit representedby general formula (3a) described above, there was synthesized acopolymer comprising the repeating unit of general formula (3a) in acontent of 70 mol %, in which a choice therefor is made such that m=0, Zis —CO—, R¹ is trifluoromethyl group, R² is difluoromethyl group, R³ ismethyl group, and R⁴, R⁵ and R⁶ are hydrogen atoms, and the norbornenetype repeating unit of general formula (7) in a content of 30 mol %, inwhich a choice therefor is made such that R¹² is tert-butoxycarbonylgroup.

There will be described the process for synthesis of the polymer ofpolynorbornene type and the conditions used therein.

In 6 mL of dichloromethane were dissolved 0.0364 g ofdi-μ-chlorobis[(η-allyl)palladium(II)] and 0.0906 g of silverhexafluoroantimonate (AgSbF₆), and the mixture was stirred at roomtemperature. After 20 min, the reaction mixture was filtered. To thefiltrate was added a solution of 2.08 g of the norbornene derivative(2-methoxy-1,1,1,3,3-pentafluoroisopropyl 2-norbornene-5-carboxylate)prepared in Example 7, 1.114 g of5-(1,1,1,3,3,3-hexafluoro-2-(tert-butoxycarbonyloxy)propan-2-yl)-2-norborneneand 0.022 g of N,N,N′,N′-tetramethyl-1,8-naphthalenediamine in 4 mL ofdichloromethane. The addition was followed by stirring at roomtemperature for further 20 hours. After that, the mixture was pouredinto 100 mL of methanol. The precipitated resin was collected byfiltration to obtain 1.34 g of the desired copolymer (yield: 42%). Asdetermined by GPC analysis, the copolymer obtained showed aweight-average molecular weight (Mw) of 19600 (calculated in polystyreneequivalent) and a dispersion (Mw/Mn) of 2.36.

Example 18

As an example of the polymer comprising the repeating unit representedby general formula (4a) described above, there was synthesized acopolymer comprising the repeating unit of general formula (4a) in acontent of 70 mol %, in which a choice therefor is made such that Z is—CO—, R¹ is trifluoromethyl group, R² is difluoromethyl group, R³ ismethyl group, and R⁴, R⁵ and R⁶ are hydrogen atoms, and the norbornenetype repeating unit of general formula (7) in a content of 30 mol %, inwhich a choice therefor is made such that R¹² is tert-butoxycarbonylgroup.

There will be described the process for synthesis of the polymer ofpolynorbornene type and the conditions used therein.

2.27 g of tricyclononene derivative prepared in Example 9, in place ofthe norbornene derivative prepared in Example 7, was reacted with 1.114g of5-(1,1,1,3,3,3-hexafluoro-2-(tert-butoxycarbonyloxy)propan-2-yl)-2-norbornenein similar manner to the polymerization conditions described in Example17 to prepare the desired copolymer (yield: 40%). As determined by GPCanalysis, the copolymer obtained showed a weight-average molecularweight (Mw) of 21500 (calculated in polystyrene equivalent) and adispersion index (Mw/Mn) of 2.42.

Example 19

Evaluation of Transparency of Polymers

In 0.45 g of propyleneglycol monomethyl ether acetate was dissolved 0.08g of the resin prepare in Example 12, and the mixture was filteredthrough a Teflon® filter with cut-off size of 0.2 μm. Then, the solutionthus obtained was applied on a calcium fluoride disk by spin coating andthe disk was baked on a hot plate at 110° C. for 120 sec to form a thinfilm with a thickness of 0.3 μm. The thin film was measured for atransmittance at the lasing wavelength of F₂ excimer laser beam of 157nm using a vacuum ultraviolet spectrophotometer (Nihon Bunko, VUV-201).

Under the same process and conditions, the resins prepared in Examples13, 14, 16 and 17 were also used to form thin films with a thickness of0.3 μm, which was then measured for a transmittance at 157 nm. As acomparative example, under the same process and conditions, a resistresin used as a resin for KrF excimer laser beam exposure; i.e.poly(p-hydroxy styrene) was also used to form a thin film with athickness of 0.3 μm, which was measured for a transmittance at 157 nm.The observed curve for a transmittance per 0.1 μm of the applied film asfor the resin obtained in Example 12 is shown in FIG. 1.

The measurement results show that the observed transmittance value foreach applied film at 157 nm was 47%/0.1 μm for the polymer resinsobtained in Example 12, 43%/0.1 μm for the polymer resins obtained inExample 13, 48%/0.1 μm for the polymer resins obtained in Example 14,50%/0.1 μm for the polymer resins obtained in Example 16, and 56%/0.1 μmofr the polymer resings obtained in Example 17, and 20%/0.1 μm forpoly(p-hydroxy styrene), respectively. From these results, it can beconfirmed that the polymer resin according to this invention exhibitshigh transparency to light at a wavelength of 157 nm.

Example 20

Exposure Performance of a Chemical Amplification Resist CompositionEmploying the Polymer According to this Invention as a Resist ResinTherefor

A chemical amplification resist composition having the followingcomposition was prepared, which used the copolymer prepared in Example13 as a resist resin therefor.

Resist Composition:

(a) the polymer (Example 13): 1.5 g

(b) a photo-acid generator (triphenylsulfonium nonaflate): 0.015 g

(c) propyleneglycol monomethyl ether acetate: 10 g

A uniformly blended mixture having the above composition was filteredthrough a Teflon® filter with cut-off size of 0.2 μm to prepare theresist composition. The resist composition was evaluated for itsexposure performance in the following procedure.

On a 4 inch silicon substrate was applied the resist composition by spincoating, and the substrate was pre-baked on a hot plate at 110° C. for 2min to form a thin-coated resist film with a thickness of 0.1 μm. Thethin-coated resist film was exposed to F₂ excimer laser as exposurelight over an exposure area of 5 mm square. Immediately after exposure,the substrate was post-baked on a-hot plate at 130° C. for 60 sec andthen the resin film exposed was developed by 60 sec immersion in a 2.38%aqueous solution of TMAH ((CH₃)₄NOH) at 23° C. After the immersion, thethin-coated resist film being developed was rinsed with pure water for60 sec.

Relationship between a light quantity for exposure and a remaining filmthickness in the exposure area was investigated. The results show thatfor the chemical amplification resist composition described above, theremaining resist film thickness reaches 0 when an exposure lightquantity from the F₂ excimer laser increases up to 12 mJ/cm², and theresist composition exhibited behaviors fit to a positive-type resist.

In addition to the chemical amplification resist composition utilizingthe copolymer prepared in Example 13 as a resist resin therefor, twotypes of chemical amplification resist compositions were prepared, whichhave a corresponding resist composition employing the copolymersobtained in Examples 14 and 17 as a resist resin therefor, respectively.These two types of chemical amplification resist compositions were alsoevaluated for their exposure performances under the same procedure andconditions. The results show that for the chemical amplification resistcomposition using the copolymer obtained in Example 14 as a resistresin, a remaining resist film thickness reaches 0 when an exposurelight quantity from the F₂ excimer laser increases up to 18 mJ/cm², andfor the chemical amplification resist composition comprising using thecopolymer obtained in Example 17, a remaining resist film thicknessreaches 0 when an exposure light quantity from the F₂ excimer laserincreases up to 17 mJ/cm². It was revealed that both the resistcompositions exhibited behaviors fit to a positive-type resist.

Example 21

The norbornene derivative obtained in Example 7 is subjected toring-opening metathesis polymerization using a metathesis catalyst.Then, a —CH═CH— moiety contained in the principal chain of the resultingring-opened polymer is hydrogenated by using a noble metal catalyst suchas palladium to prepare a desired polymer having a saturated principalchain. This polymer is also evaluated for a transmittance of a coatedresin film at 157 nm under the procedure and the conditions described inExample 19. Said polymer exhibits excellent transparency to light at awavelength of 157 nm.

INDUSTRIAL APPLICABILITY

A monomer according to this invention makes use of a fluorine-containingacetal or ketal structure as a moiety to be subjected to anacid-catalytic dissociation with a proton acid derived from a photo-acidgenerator as well as a principal frame that contains a carbon-carbondouble bond exhibiting polymerization activities adaptable to additionpolymerization or ring-opening metathesis polymerization. Accordingly,in a polymer of this invention that comprises a repeating unit beingobtainable by polymerizing said monomer, optical absorption to exposurelight at 180 nm or shorter is significantly reduced. Such a resist ofchemical-amplification type that employs the polymer of this inventioncan make the best use of the aforementioned properties thereof, so thatthe resist is superior in transparency to exposure light at 180 nm orshorter. For instance, when the resist is applied to photolithographyusing F₂ excimer laser at a lasing wavelength of 157 nm for exposure, itallows to avoid the main cause for inhibition of effective transmissionof exposure light to a substrate surface, i.e., such a phenomenon thatmajor part of the exposure light is absorbed by the resin itself placingnear top surface of the resist. Accordingly, fine patterning requiredfor process of manufacturing a semiconductor device can be successfullyconducted by applying the chemical-amplification-type resist of thisinvention to photolithography using exposure light at 180 nm or shorter,for example, F₂ excimer laser at an emission wavelength of 157 nm.

1. A monomer containing a carbon-carbon double bond exhibitingpolymerization activity thereby and having a fluorine-containingstructure in the molecule, wherein the monomer is a (meth)acrylatederivative having a fluorine-containing structure represented by generalformula (2):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a fluorinated alkyl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group; R³ represents a radical selected from the groupconsisting of a hydrogen atom, a linear, branched or cyclic alkyl group,an alkoxy-substituted alkyl group, a fluorinated alkyl group, an arylgroup, a fluorinated aryl group, an aralkyl group and a fluorinatedaralkyl group having 1 to 20 carbon atoms; R⁴ and R⁵ independentlyrepresent a hydrogen atom or a fluorine atom; and R⁶ represents ahydrogen atom, a fluorine atom, a methyl group or a trifluoromethylgroup.
 2. A polymer being producible by polymerization of one or moremonomer materials containing a carbon-carbon double bond exhibitingpolymerization activity thereby, wherein the polymer comprises arepeating unit being obtainable by addition polymerization of at leastone of the monomer as claimed in claim 1, as one of the repeating unitscontained in the polymer.
 3. A resist composition ofchemical-amplification-type comprising a resist resin and aphoto-sensitizer therefor, wherein the composition comprises the polymeras claimed in claim 2 as said resist resin.
 4. A monomer containing acarbon-carbon double bond exhibiting polymerization activity thereby andhaving a fluorine-containing structure in the molecule, wherein themonomer is a norbornene derivative or tetracyclododecene derivativehaving a fluorine-containing structure represented by general formula(3):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aryl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; X¹ and X² independently represent a hydrogenatom or a methyl group; Z represents —CO—; and m is 0 or
 1. 5. A polymerbeing producible by polymerization of one or more monomer materialscontaining a carbon-carbon double bond exhibiting polymerizationactivity thereby, wherein the polymer comprises a repeating unit beingobtainable by ring-opening metathesis polymerization of at least one ofthe monomer as claimed in claim 4 and then hydrogenating a —CH═CH—moiety resulting therefrom, as one of the repeating units contained inthe polymer.
 6. A resist composition of chemical-amplification-typecomprising a resist resin and a photo-sensitizer therefor, wherein thecomposition comprises the polymer as claimed in claim 5 as said resistresin.
 7. A monomer containing a carbon-carbon double bond exhibitingpolymerization activity thereby and having a fluorine-containingstructure in the molecule, wherein the monomer is a tricyclononenederivative having a fluorine-containing structure represented by generalformula (4):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aryl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; and Z represents —CO—, a methylene group or alinking group composed of a carbon-oxygen bond.
 8. A polymer beingproducible by polymerization of one or more monomer materials containinga carbon-carbon double bond exhibiting polymerization activity thereby,wherein the polymer comprises a repeating unit being obtainable byring-opening metathesis polymerization of at least one of the monomer asclaimed in claim 7 and then hydrogenating a —CH═CH— moiety resultingtherefrom, as one of the repeating units contained in the polymer.
 9. Aresist composition of chemical-amplification-type comprising a resistresin and a photo-sensitizer therefor, wherein the composition comprisesthe polymer as claimed in claim 8 as said resist resin.
 10. A polymercomprising one or more repeating units being obtainable by additionpolymerization of a (meth)acrylate derivative, wherein the unit has afluorine-containing structure represented by general formula (2a):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a fluorinated alkyl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl; R³ represents a radical selected from the groupconsisting of a hydrogen atom, a linear, branched or cyclic alkyl group,an alkoxy-substituted alkyl group, a fluorinated alkyl group, an arylgroup, a fluorinated aryl group, an aralkyl group and a fluorinatedaralkyl group having 1 to 20 carbon atoms; R⁴ and R⁵ independentlyrepresent a hydrogen atom or a fluorine atom; and R⁶ represents ahydrogen atom, a fluorine atom, a methyl group or a trifluoromethylgroup.
 11. The polymer as claimed in claim 10, comprising, in additionto said repeating unit having a fluorine-containing structure, one ormore repeating units selected from the group consisting of a repeatingunit represented by general formula (5):

wherein R⁷ and R⁸ are independently a hydrogen atom or a fluorine atom;R⁹ is a hydrogen atom, a fluorine atom, a methyl group or atrifluoromethyl group; R¹⁰ represents a radical selected from the groupconsisting of a hydrogen atom; a linear, branched or cyclic alkyl groupand fluorinated alkyl group having 1 to 20 carbon atoms; a groupremovable by an acid; a bridged cyclic hydrocarbon group having 7 to 13carbon atoms containing a group removable by an acid thereon andnorbornane-2,6-carbolactone-5-yl group; a repeating unit represented bygeneral formula (6):

wherein R¹¹ represents a hydrogen atom or a group removable by an acid;a repeating unit represented by general formula (7):

wherein R¹² represents a hydrogen atom or a group removable by an acid;a tetrafluoroethylene radical represented by formula (8):—CF₂—CF₂—  (8) a repeating unit represented by general formula (9):

wherein R¹³ and R¹⁴ independently represent a hydrogen atom or afluorine atom; R¹⁵ represents a hydrogen atom, a fluorine atom, a methylgroup or a trifluoromethyl group; R¹⁶ represents a hydrogen atom, ahydroxy group, hydroxy alkyl group or an acid-dissociable organic grouphaving 20 or less carbon atoms which can generate a carboxy grouptherefrom by its decomposition by an acid; a repeating unit representedby general formula (10):

wherein R¹³ and R¹⁴ independently represent a hydrogen atom or afluorine atom; R¹⁵ represents a hydrogen atom, a fluorine atom, a methylgroup or a trifluoromethyl group; R¹⁶ represents a hydrogen atom, ahydroxy group, a hydroxy alkyl group or an acid-dissociable organicgroup having 20 or less carbon atoms which can generate a carboxy grouptherefrom by its decomposition by an acid; a repeating unit representedby general formula (11):

wherein R¹³ and R¹⁴ is independently a hydrogen atom or a fluorine atom;R¹⁵ represents a hydrogen atom, a fluorine atom, a methyl group or atrifluoromethyl group; R¹⁶ represents a hydrogen atom, a hydroxy group,a hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid; a repeating unit represented by generalformula (12):

wherein R¹³ and R¹⁴ is independently a hydrogen atom or a fluorine atom;R¹⁵ represents a hydrogen atom, a fluorine atom, a methyl group or atrifluoromethyl group; R¹⁶ represents a hydrogen atom, a hydroxy group,a hydroxy alkyl group or an acid-dissociable organic group having 20 orless carbon atoms which can generate a carboxy group therefrom by itsdecomposition by an acid; and an anhydrous succindiyl represented byformula (13):


12. The polymer as claimed in claim 10, wherein the polymer comprisessaid repeating unit represented by general formula (2a) in a content ofat least 5 to 90 mol % to the total number of the repeating unitscomposing the polymer.
 13. The polymer as claimed in claim 10, wherein aweight-average molecular weight of the polymer is selected in the rangeof 2,000 to 200,000.
 14. A resist composition ofchemical-amplification-type comprising a resist resin and aphoto-sensitizer, wherein the composition comprises one or more of thepolymers as claimed in claim 10 as said resist resin and at least aphoto-acid generator capable of generating an acid by exposure light assaid photo-sensitizer; and the content of the photo-acid generator tothe total amount of the polymer and the photo-acid generator is selectedin the range of 0.2 to 30 wt %.
 15. A process for formation of patternby photolithography utilizing a chemical-amplification-type resist,comprising at least the steps of: forming a film of thechemical-amplification-type resist as claimed in claim 14 applied onto asubstrate to be processed for formation of pattern thereon; irradiatingthe substrate with light at a wavelength of 130 to 180 nm as exposurelight in accordance with a pattern to be formed to expose said film ofthe chemical-amplification-type resist; carrying out baking treatmentfor said exposed film of the chemical-amplification-type resist; andcarrying out developing treatment for said film treated by baking. 16.The process for formation of pattern as claimed in claim 15, wherein thelight at a wavelength of 130 to 180 nm used in said exposure step is F₂excimer laser beam.
 17. A polymer comprising one or more repeating unitsbeing obtainable by addition polymerization of a norbornene derivativeor a tetracyclododecene derivative, wherein the unit has afluorine-containing structure represented by general formula (3a):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aryl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; X¹ and X² independently represent a hydrogenatom or a methyl group; Z represents —CO—; and m is 0 or
 1. 18. Thepolymer as claimed in claim 17, wherein the polymer comprises saidrepeating unit represented by general formula (3a) in a content of atleast 5 to 90 mol % to the total number of the repeating units composingthe polymer.
 19. A resist composition of chemical-amplification-typecomprising a resist resin and a photo-sensitizer, wherein thecomposition comprises one or more of the polymers as claimed in claim 17as said resist resin and at least a photo-acid generator capable ofgenerating an acid by exposure light as said photo-sensitizer; and thecontent of the photo-acid generator to the total amount of the polymerand the photo-acid generator is selected in the range of 0.2 to 30 wt %.20. A polymer comprising one or more repeating units being obtainable byaddition polymerization of a tricyclononene derivative, wherein the unithas a fluorine-containing structure represented by general formula (4a):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aryl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; and Z represents —CO—, a methylene group or alinking group composed of a carbon-oxygen bond.
 21. The polymer asclaimed in claim 20, wherein the polymer comprises said repeating unitrepresented by general formula (4a) in a content of at least 5 to 90 mol% to the total number of the repeating units composing the polymer. 22.A resist composition of chemical-amplification-type comprising a resistresin and a photo-sensitizer, wherein the composition comprises one ormore of the polymers as claimed in claim 20 as said resist resin and atleast a photo-acid generator capable of generating an acid by exposurelight as said photo-sensitizer; and the content of the photo-acidgenerator to the total amount of the polymer and the photo-acidgenerator is selected in the range of 0.2 to 30 wt %.
 23. A process forformation of pattern by photolithography utilizing achemical-amplification-type resist, comprising at least the steps of:forming a film of the chemical-amplification-type resist as claimed inclaim 22 applied onto a substrate to be processed for formation ofpattern thereon; irradiating the substrate with light at a wavelength of130 to 180 nm as exposure light in accordance with a pattern to beformed to expose said film of the chemical-amplification-type resist;carrying out baking treatment for said exposed film of thechemical-amplification-type resist; and carrying out developingtreatment for said film treated by baking.
 24. A polymer comprising oneor more repeating units being obtainable by ring-opening polymerizationof a norbornene derivative or tetracyclododecene derivative and thenhydrogenating a —CH═CH— moiety resulting therefrom, wherein the unit hasa fluorine-containing structure represented by general formula (3b):

wherein R¹ and P² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aryl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; X¹ and X² independently represent a hydrogenatom or a methyl group; Z represents —CO—, a methylene group or alinking group composed of a carbon-oxygen bond; and m is 0 or
 1. 25. Thepolymer as claimed in claim 24, wherein the polymer comprises saidrepeating unit represented by general formula (3b) in a content of atleast 5 to 90 mol % to the total number of the repeating units composingthe polymer.
 26. A resist composition of chemical-amplification-typecomprising a resist resin and a photo-sensitizer, wherein thecomposition comprises one or more of the polymers as claimed in claim 24as said resist resin and at least a photo-acid generator capable ofgenerating an acid by exposure light as said photo-sensitizer; and thecontent of the photo-acid generator to the total amount of the polymerand the photo-acid generator is selected in the range of 0.2 to 30 wt %.27. A process for formation of pattern by photolithography utilizing achemical-amplification-type resist, comprising at least the steps of:forming a film of the chemical-amplification-type resist as claimed inclaim 26 applied onto a substrate to be processed for formation ofpattern thereon; irradiating the substrate with light at a wavelength of130 to 180 nm as exposure light in accordance with a pattern to beformed to expose said film of the chemical-amplification-type resist;carrying out baking treatment for said exposed film of thechemical-amplification-type resist; and carrying out developingtreatment for said film treated by baking.
 28. A polymer comprising oneor more repeating units being obtainable by ring-opening polymerizationof a tricyclononene derivative and then hydrogenating a —CH═CH— moietyresulting therefrom, wherein the unit has a fluorine-containingstructure represented by general formula (4b):

wherein R¹ and R² independently represent a radical selected from thegroup consisting of a hydrogen atom, a linear, branched or cyclic alkylgroup, a fluorinated alkyl group, an aryl group and a fluorinated arylgroup having 1 to 20 carbon atoms; and at least one of R¹ and R² is saidfluorinated alkyl group or said fluorinated aryl group; R³ represents aradical selected from the group consisting of a hydrogen atom, a linear,branched or cyclic alkyl group, an alkoxy-substituted alkyl group, afluorinated alkyl group, an aryl group, a fluorinated aiyl group, anaralkyl group and a fluorinated aralkyl group having 1 to 20 carbonatoms; R⁴ and R⁵ independently represent a hydrogen atom or a fluorineatom; R⁶ represents a hydrogen atom, a fluorine atom, a methyl group ora trifluoromethyl group; and Z represents —CO—, a methylene group or alinking group composed of a carbon-oxygen bond.
 29. The polymer asclaimed in claim 28, wherein the polymer comprises said repeating unitrepresented by general formula (4b) in a content of at least 5 to 90 mol% to the total number of the repeating units composing the polymer. 30.A resist composition of chemical-amplification-type comprising a resistresin and a photo-sensitizer, wherein the composition comprises one ormore of the polymers as claimed in claim 28 as said resist resin and atleast a photo-acid generator capable of generating an acid by exposurelight as said photo-sensitizer; and the content of the photo-acidgenerator to the total amount of the polymer and the photo-acidgenerator is selected in the range of 0.2 to 30 wt %.
 31. A process forformation of pattern by photolithography utilizing achemical-amplification-type resist, comprising at least the steps of:forming a film of the chemical-amplification-type resist as claimed inclaim 30 applied onto a substrate to be processed for formation ofpattern thereon; irradiating the substrate with light at a wavelength of130 to 180 nm as exposure light in accordance with a pattern to beformed to expose said film of the chemical-amplification-type resist;carrying out baking treatment for said exposed film of thechemical-amplification-type resist; and carrying out developingtreatment for said film treated by baking.